Radio in The United States - Broadcast Call Signs

Broadcast Call Signs

Further information: List of radio stations in North America by media market

While broadcast radio stations will often brand themselves with plain-text names, identities such as "cool FM", "rock 105" or "the ABC network" are not unique. Another station, in another city or country, may (and often will) have a similar brand; the name of a broadcast station for legal purposes is, therefore, normally its ITU call sign.

Broadcast stations in North America generally use call letters in the international series, with common conventions followed in each country. In the United States, the first letter generally is K for stations west of the Mississippi River and W for those east of the Mississippi; all new call signs have had four characters since 1922, although there are historical three-character calls still in use (such as WOR in New York City, WBZ in Boston, WOL in Washington DC, WSB in Atlanta, WSM in Nashville, WMC in Memphis, WGN in Chicago, KLZ and KOA in Denver, KSL in Salt Lake City, KEX in Portland, Oregon, KFI in Los Angeles and KGU in Hawaii. The ITU has allocated call signs starting with N, as well as AA through AN, to the United States, but those prefixes are not in use on any AM or FM radio station.

There are exceptions to the east-west rule (such as KDKA in Pittsburgh and WFAA in Dallas-Fort Worth, Texas); these are historical artifacts from a rule change in the 1930s, and most of the exceptions are located in the states immediately adjacent to the river. The westernmost station in the continental United States beginning with W is WOAI in San Antonio, Texas. WVUV-LP in Pago Pago, American Samoa is the westernmost station with a W call sign. KYW in Philadelphia is the easternmost station with a K call sign.

All time-broadcasting stations have a three- or four-letter call sign, beginning with WWV. The three current government-operated time stations (WWV, longwave sister station WWVB and WWVH) are located in Fort Collins, Colorado and Kekaha, Hawaii respectively, so all would normally use call signs beginning with K.

The US government-operated international broadcaster Voice of America no longer has call signs assigned to it; in contrast, Radio Canada International's transmitter in Sackville, New Brunswick was still assigned CKCX-SW until its 2012 shutdown. Privately-operated shortwave stations (such as WWCR and CFRX) also have call signs.